My cat scares the dog

There is a female dog in heat, and there is a male dog that wants to reach her. And then there is Sissi, a red female cat, that she'll never allow him to get his reward. And so, this is what happen everytime that poor little dog try to come near our neighbour's female dog and Sissi is around.

PS: we made this video because we know that anything wrong it will be happen, because we know really well our cat and that dog.